Outdated hardware is slowing down the US Marine Corps' migration toWindows 10. The Marines had estimated that they could update 60 to 70percent of their computers remotely, but that figure has been revisedto 10 percent after they ran into problems with older hardware that "ishaving more difficulty accepting Windows 10 than hardware that is new."Having to perform the updates physically is adding time and cost to theproject. The Department of Defense's (DOD) upgrade to Windows 10 has a"secure host baseline," which is important because it will be the firsttime DOD has common security configurations across all PCs. The NationalSecurity Agency's Information Assurance Directorate said that migratingto Windows 10 with or without the baseline security configuration wouldprovide better security than not upgrading at all.

For such a large scale "update" surely a quick count or small study was made of the existing hardware base ?

It seems Win10 still has a long way to go to become the defacto O/S of choice, I haven't yet met anyone running it whom thought it represented anything other than another industry led "update to keep us in business" cycle.